CMP process

Abstract

The optimization of a CMP process provides the use of an auxiliary layer ( 4 ) between a dielectric ( 1 ) in the vicinity of patterned portions and a layer of a liner ( 2 ). If the liner ( 2 ) is perforated in the CMP process, then the undercutting of the liner ( 2 ) by the chemical removal of the auxiliary layer ( 4 ) simplifies the process overall. Advantages are significantly lower defect densities due to CMP scratches, fewer short circuits, fewer alignment errors.

What is claimed is:  
     
       1. A method for producing a metal contact in a dielectric comprising the steps of forming a contact via in said dielectric; 
       providing a liner made of titanium or a titanium compound on the whole area of said dielectric and in said contact via;  
       providing a metalization on said whole area, on said dielectric and in said contact via, wherein at least in the surroundings of said contact via providing an auxiliary layer on said dielectric between said dielectric and said liner, perforating said liner and said auxiliary layer to form a plurality of perforations; undercutting said liner by etching said liner through said perforation, and removing said metalization on said liner and said auxiliary layer by a Chemical Mechanical Polishing process, said process stopping on said dielectric, whereby upon perforation of said liner and said auxiliary layer an under etch of said liner by removal of said auxiliary layer is effected such that the liner lying thereon is lifted off.  
     
     
       2. The method as claimed in  claim 1 , wherein the auxiliary layer has a layer thickness in the range of 20 to 100 am. 
     
     
       3. The method as claimed in  claim 1 , wherein the auxiliary layer is used at least partly as a hard mask for the patterning and preceding the etching by dry etching. 
     
     
       4. The method as claimed in  claim 1 , wherein the auxiliary layer is detected by an etching stop detection signal during the CMP process. 
     
     
       5. The method as claimed in  claim 1 , wherein an additional wet-chemical cleaning step is carried out at the end of the etching. 
     
     
       6. The method as claimed in  claim 1 , wherein the auxiliary layer is composed of diamond-like carbon, carbon polymers or of porous material. 
     
     
       7. The CMP process as claimed in  claim 6 , wherein the auxiliary layer is used in conjunction with a CARL resist as bottom resist.